This application claims priority of pending application filed in Belgium on Jan. 8, 1997, Application Number 97100185.4 to the same inventors as the present application.
The present invention relates to polymer-modified bituminous compositions, used for roofing and waterproofing membranes or material.
Physical properties of a bituminous composition used for roofing and waterproofing membranes or material such as low temperature break resistance, flexibility, high temperature flow resistance and viscosity can be improved, as disclosed in U.S. Pat. No. 4,530,652, by incorporating radial elastomeric block copolymers whose structure is defined by the general formula (A-B)nY wherein Y is the residue of a polyfunctional coupling agent, (A-B) represents a single arm constituted of a polydiene block B and a polyvinyl aromatic endblock A, and xe2x80x9cnxe2x80x9d represents the number of arms (A-B). Bituminous compositions comprising such copolymers, when used for roofing or waterproofing membranes, indeed provide good performance properties. However, the latter are obtained at the detriment of other physical properties limiting their broader applications. For example, when those elastomeric block copolymers are added to a bituminous material to improve high temperature properties, the low temperature performance is impaired. Likewise, when both high and low temperature properties are met, the viscosity of the roofing materials is such as to render its handling inoperable with standard equipment.
In U.S. Pat. No. 4,196,115, two radial elastomeric block copolymers, one having a low, the other having a high molecular weight, (or, alternatively, one radial of high molecular weight and one linear elastomeric block copolymer of low molecular weight) are blended together with a bituminous component to prepare a roofing material. Both copolymers are selected in such a way that the final bituminous composition yields the desirable high and low temperature properties satisfying tests which determine the said properties for ultimate use of the roofing membranes. Unfortunately, this process implies the mixture of at least two compounds, namely two separately-prepared copolymers, with a bituminous component in order to obtain compositions that give the desired properties to the final membranes.
The present invention aims at new bituminous compositions which enable to enlarge the range of service temperatures of roofing and waterproofing membranes or material, without impairing appropriate viscosities that allow an easy handling with standard installation equipment, by proposing bituminous compositions that do not require the presence of two or more separately-prepared (co)polymers in bituminous compositions in order to be especially suitable to those applications.
An objective of this invention is to provide improved bituminous compositions which are suitable for roofing and waterproofing material or membranes.
A further objective of this invention is to disclose a bituminous composition which does not require the presence of more than one copolymer component.
A further objective of this invention is to enlarge the range of the working temperatures for roofing and waterproofing membranes or material which are made from these bituminous compositions.
A further objective of this invention is to ensure appropriate dynamic viscosities to the bituminous composition such that an easy handling of the ultimate roofing and waterproofing material or membranes be possible with standard installation equipments.
The present invention relates to bituminous compositions, used for roofing and waterproofing membranes or material, which consist of a bituminous component and one or more rubbery components constituted of linear polyvinyl aromatic polydiene block copolymer having an asymmetrical structure, the term xe2x80x9casymmetricalxe2x80x9d meaning that the endblocks in the molecular structure are polyvinyl aromatic segments of at least two different lengths, one short and one long.
More particularly, the bituminous composition of this invention is constituted of a bituminous component and at least one elastomeric block copolymer whose molecular structures are described by the general formula A1-X-A2 in which A1 and A2 represent polymeric endblocks of monovinyl aromatic monomers and X an elastomeric segment. These asymmetrical elastomeric block copolymers are characterised by endblocks A1 and A2 having at least two different molecular weights, one xe2x80x9chighxe2x80x9d and one xe2x80x9clowxe2x80x9d.
It has been unexpectedly found that improved physical properties at both high and low temperature of a bituminous composition are obtained by incorporating small amounts of such asymmetrical elastomeric block copolymers in a bituminous composition. The copolymer-containing bituminous composition and obtained by this invention is surprisingly provided with all the desired physical performance that gives to final roofing and waterproofing membranes or material, broader ranges of working temperatures and appropriate dynamic viscosities required by standard application equipments. The improved ranges of service temperatures, which are defined as the difference between the softening point and the cold-bending temperature, give to the ultimate membranes both good high and low temperature performance sot that they can be used under prevailing environmental conditions in any geographical location.